I downloaded a FLAC album from online web store and it appears that the files I've downloaded are 24-bit. it's not a hd web store like hdtracks, it's generally a CD 16-bit 44.1kHz store with either FLAC or MP3 to choose from in its offerings.

I'm wondering whether the 24-bit files are real and were supplied as 24-bit from the label and they just didn't label it correctly on the download page, or whether there was an encoding error or just somehow it made its way from 16-bit files to 24-bit FLACs.

Is there a way I can definitively tell or analyze it (looking at spectral maybe) to see if it's been upconverted? Are there certain algorithms and 'good jobs' that can be done to make its 16->24 upconversion undetectable?

Thanks guys (and yeah thanks greynol for pointing that out about the spectral view), I now have confirmation from the webstore that it was an encoding error when ripping from the physical CD disc to upload on the store.

I'd like to see if those ideas above show anything.

So Now that I know more of how the 24-bit files were created: well obviously it was somewhere at the FLAC encoder level? Looks like they accidentally had 24-bit (flac) output selected in whatever ripping program they used, and that's how it happened. probably first extracted as 16-bit wav, but then converted from that into 24-bit flac, you think? with that in mind, any more clarity of how one could detect a flac.exe-produced 24-bit blow-up job?

Also, get this: their response to me pointing out the error, was such that they weren't actually to take any action unless I requested them to. they merely said 'This does not detract from the files but means that they are slightly larger than they need to be.' They actually are twice the size they need to be.

They seemed content with me wasting hard drive space for absolutely no reason, just because they, a professional music downloads web store, made a mistake when ripping the files.

Lazy.

NOW, after telling them I either want a refund or re-ripped files from the disc, within 5 minutes they have come back and said they have new (fixed) 16-bit files for you on the store. they obviously didn't re-rip the files from the disc, they clearly just downconverted the 24-bit files to 16-bit, right??? and unless that's done with a really good dithering algorithm, that could be inferior to an original straight rip from the 16-bit, right?

what's the bet they used some dodgy program (like, I dunno, is dbpoweramp a good example of dodgy?) to downconvert it again? Should I continue to not be satisfied and point this out to them, and demand a proper true lossless re-rip with no mucking around, and also is there a way to detect whether something's been (with damage), downconverted from 24-bit to 16-bit (I guess this is impossible without comparing it to an original perfect CD rip from the original unprocessed 16-bit.....?)?

ah - started writing this before finishing reading 2Bdecided's reply.....well with this in mind (16->24->16), is there any way I can at least prove the 24->back to->16 bit, bit?

Are you sure? I just tried upconverting a 16 bit album in FLAC to 24 bit, and the resulting FLACs are almost the same size at the originals.

As a sidenote, I scanned my entire FLAC collection with my script, and I found an oddity: the album "Smash" by The Offspring only has 15 effective bits (out of 16, it's a CD rip). I wonder why that is.

Are you sure? I just tried upconverting a 16 bit album in FLAC to 24 bit, and the resulting FLACs are almost the same size at the originals.

When I convert my originally-provided and bloated 24-bit files to 16-bit flac with foobar (and yes I've checked compression levels too, to make them equivalent, as much as I can guess), it's more than a ratio of 2:1. so yes it's definitely twice too much pointless stuff they were making me download and store on my hard drives.

QUOTE (greynol @ Nov 6 2012, 17:59)

You would really have to go out of your way to do 16 -> 24 -> 16 for it to result in audible degradation.